Concurrent Covalent and Supramolecular Polymerization

Covalent and supramolecular polymerizations, both of which offer their own unique advantages, have emerged as popular strategies for making artificial materials. Herein, we describe a concurrent covalent and supramolecular polymerization strategy—namely, one which utilizes 1) a bis‐azide‐functionalized diazaperopyrenium dication that undergoes polymeriation covalently with a bis‐alkyne‐functionalized biphenyl derivative in one dimension as a result of a rapid and efficient β‐cyclodextrin(CD)‐accelerated, cucurbit[6]uril(CB)‐templated azide–alkyne cycloaddition, while 2) the aromatic core of the dication is able to dimerize in a criss‐cross fashion by dint of π–π interactions, enabling simultaneous supramolecular assembly, resulting in an extended polymer network in an orthogonal dimension.     

Ion Exchange Separation of Eu3+ from Different Salt Solutions

Two samples of potassium zinc hexacyanoferrate were prepared using two different ratios of the initial materials. The distribution coefficient of Eu³⁺ on the two samples was determined. The effect of the cation concentration in the aqueous phase on the adsorption of Eu³⁺ was also studied. The mechanism of the exchange process was described on the light of the data obtained, and the equilibrium constant of the exchange reaction was also calculated.     

A neutral redox-switchable [2]rotaxane

A limited range of redox-active, rotaxane-based, molecular switches exist, despite numerous potential applications for them as components of nanoscale devices. We have designed and synthesised a neutral, redox-active [2]rotaxane, which incorporates an electron-deficient pyromellitic diimide (PmI)-containing ring encircling two electron-rich recognition sites in the form of dioxynaphthalene (DNP) and tetrathiafulvalene (TTF) units positioned along the rod section of its dumbbell component. Molecular modeling using MacroModel guided the design of the mechanically interlocked molecular switch. The binding affinities in CH(2)Cl(2) at 298 K between the free ring and two electron-rich guests--one (K(a) = 5.8 × 10(2) M(-1)) containing a DNP unit and the other (K(a) = 6.3 × 10(3) M(-1)) containing a TTF unit--are strong: the one order of magnitude difference in their affinities favouring the TTF unit suggested to us the feasibility of integrating these three building blocks into a bistable [2]rotaxane switch. The [2]rotaxane was obtained in 34% yield by relying on neutral donor-acceptor templation and a double copper-catalysed azide-alkyne cycloaddition (CuAAC). Cyclic voltammetry (CV) and spectroelectrochemistry (SEC) were employed to stimulate and observe switching by this neutral bistable rotaxane in solution at 298 K, while (1)H NMR spectroscopy was enlisted to investigate switching upon chemical oxidation. The neutral [2]rotaxane is a chemically robust and functional switch with potential for applications in device settings.     

Colouring Agents for SBR Vulcanizates and Their Effects on Ageing and UV Radiation Resistance

Summary: Metal free and some metal-perylene polymers as well as some metal phthalocyanine polymers were incorporated into styrene butadiene rubber (SBR) compounds as colouring agents. The ageing and UV resistance of the vulcanizates obtained were studied in terms of their mechanical properties. The results obtained revealed that cobalt perylene and cobalt phthalocyanine polymers showed superior performance in SBR vulcanizates against thermal ageing and UV radiation. The optimum concentration of cobalt phthalocyanine polymer was found to be 1 phr (parts per hundred parts of rubber).     

Separation of some lanthanides on potassium zinc hexacyanoferrate ion exchanger

Adsorption behaviour of Sm³⁺, Gd³⁺, Tb³⁺ and Tm³⁺ on potassium zinc hexacyanoferrate (PZF) was investigated. The effect of K⁺ and Zn²⁺ concentrations on the distribution coefficient was studied. The mechanism of ion exchange and possible separation of the lanthanides used are discussed.     

Effect of octupole and higher deformations on Coulomb barrier

The effect of octupole deformation, β₃, and the higher multipole deformations, β₆ and β₈, on the distribution of barriers in orientation degrees of freedom, is studied. Coulomb barriers are derived in the frame work of the double folding model with the realistic M3Y nucleon–nucleon interaction and its density dependent version. ⁴⁸Ca + ²⁴⁴Pu spherical-deformed nuclear interacting pair is considered, as an example, to study the effect of deformation parameters on the height and position of the Coulomb barrier. Although the dependence of the Coulomb barrier parameters on the higher deformations is complicated, numerically, if it is treated in microscopic way, we found a simple linear variation of barrier parameters with the different orders of deformation. We found that the variation of the barrier parameters with deformation exactly follows the change of the half density radius of the deformed nucleus in the direction of the separation vector between the centers of mass of the interacting nuclei. This suggests a simple and straightforward way to predict the behavior of the barrier parameters with different orders of deformations. We compared the results of present work with a similar recent study of the same quantities based on simple expression derived by Wong for the Coulomb part and proximity approach for the nuclear part of heavy ion potential, respectively.     

Adsorption behaviour of some lanthanides on zirconium phosphate silicate (ZPS) in mineral acids

The distribution coefficients of tervalent eruopium, terbium, thulium and scandium between zirconium phosphate silicate and mineral acids have been determined. The distribution coefficients were found to change from one element to another and to depend on the acid used and its concentration. Separation factors were calculated and a separation scheme for these elements was worked out.     

A method for determining foil thicknesses in TEM by using convergent beam electron diffraction under weak beam conditions

In the present work, convergent beam electron diffraction was studied in zirconium (a material of intermediate atomic number) at 300 keV, under weak beam diffraction conditions. For a particular thickness, the details in an observed low order disc were matched to those calculated using the multibeam dynamical theory. This presents the possibility of determining foil thickness over a wide range, with an estimated experimental accuracy of ≈7% or less. In contrast to other convergent beam techniques, the present method, which uses weak beam conditions, can employ commonly-occurring low order reflections to extract thicknesses.

A simple equation based on the two beam approximation, is derived to determine foil thickness (to within ≈ 10%) without resorting to detailed image matching. This equation can be used for a rough estimate of foil thickness while carrying out TEM observations.